The invention relates to a machine tool for processing crankshafts and in particular drilling oil holes as oblique drill holes in crankshafts.
Crankshafts display a plurality of main bearings along their main axes and lifting bearings at the cranks. To lubricate the lifting bearings, oblique drill holes are produced which extend from one lifting bearing through the offest to the main bearing. Such drill holes are relatively long and the production of these holes requires very accurate oblique alignment of the crankshaft.
A machine tool for producing drill holes in crankshafts is disclosed in U.S. Pat. No. 5,759,140. This machine tool comprises a workpiece carrier with two clamping devices which allow two crankshafts to be processed synchronously. The workpiece carrier can be pivoted around a horizontal transverse axis and it can assume such an inclined position that the horizontally aligned and horizontally guided tools hit upon the crankshafts at the desired drilling angle. To produce a plurality of drill holes at different locations along the crankshaft, the spindle box is controllably displaced in vertical direction. Drill bushings are associated to the tools (drills) inserted in the spindles. The tools and drill bushings are taken from a tool magazine and can be automatically exchanged.